Method and means for detecting the approaching end of a thread and a bobbin therefor

ABSTRACT

This invention teaches a bobbin having a plurality of parts on which a continuous length of thread may be wound such that when the main portion or length of the thread is unwound from the bobbin, a terminal portion or length of the thread may be utilized to indicate the approaching end of the thread. The bobbin includes parts about which the thread may be wound in a continuous manner but to separate portions of the thread from each other to enable the winding of the thread such that the terminal end of the thread may be detected with the use of a sensor structure.

United States Patent [1 1 Winberg Oct. 29, 1974 1 1 METHOD AND MEANS FORDETECTING THE APPROACHING END OF A THREAD AND A BOBBIN THEREFOR {76]lnventor: Ragnar William Winberg, 94

Searing Ave., Mineola, NY. 11501 1221 Filed: Mar. 26, 1973 [21] Appl.No: 344,743

[52] U.S. Cl 250/571, 250/222 R, 139/273 A, 242/1184, 242/18 [51] Int.Cl. G011) 7/12 [58] Field 01 Search 250/219 S, 222 R, 561, 250/571;356/159, 239; 139/273 A [56] References Cited UNlTED STATES PATENTS2,3405 74 2/1944 Ashworth 242/118.4 2,926,860 3/1960 Pomarico 250/219 FRSampson 250/219 X Kent ct a1. 250/219 X [57] ABSTRACT This inventionteaches a bobbin having a plurality of parts on which a continuouslength of thread may be wound such that when the main portion or lengthof the thread is unwound from the bobbin, a terminal portion or lengthof the thread may be utilized to indicate the approaching end of thethread. The bobbin includes parts about which the thread may be wound ina continuous manner but to separate portions of the thread from eachother to enable the winding of the thread such that the terminal end ofthe thread may be detected with the use of a sensor structure.

6 Claims, 6 Drawing Figures METHOD AND MEANS FOR DETECTING THEAPPROACHING END OF A THREAD AND A BOBBIN THEREFOR BACKGROUND OF THEDISCLOSURE At present in commercial sewing machines, a bobbin isprovided with thread that forms the lower stitch. This lower stitch isengaged by thread forming the upper stitch that is usually supplied froma spool mounted on and in full view of the operator. Thus, the operatormay easily see when the thread on the spool is approaching its end and,therefore, may readily change the same. Unfortunately, however, there isno way for the operator, who is intent upon and absorbed in the sewingoperation, to know when the bobbin is about to run out of thread.

Contributing reasons are that the operator is too intent upon performingthe sewing operation to pay attention to the thread on the bobbin andalso because the bobbin is usually contained within a bobbin housingthat is mounted beneath the stitching plate and obscured within thehousing and, therefore, is not readily accessible for easy and rapidviewing. Hence, it often happens that the absorbed sewing machineoperator will continue to sew even after the bobbin has run out ofthread. This results in a line of stitching in which only the upperthread will be sewn without a locking stitching in the lower threadcoming fromthe bobbin.

SUMMARY OF THE INVENTION The desideratum of the invention is to providea unique bobbin, method of winding the same and a method and means fordetermining when the thread on the bobbin is approaching the end of itssupply without requiring the operator to stop from time to time tophysically remove the bobbin from its nest or housing to visually checkthe same.

An object ofthe invention is to provide a bobbin that has provisionthereon for winding a continuous length of thread in two separateportions such that the unwinding of the terminal portion may be detectedand an indication provided to the operator without requiring theoperator to divert attention to the condition of the thread on thebobbin.

Another object is to provide a novel method of winding a bobbin toenable the detection and to signal the approaching end of the thread.

Still a further object is to provide a sensing structure cooperable withthe bobbin to sense and to afford a method of sensing the approachingend of the thread without interfering with the functions of the sewingoperution.

The above description, as well as further objects, features andadvantages of the present invention, will be more fully appreciated byreference to the following detailed description of a presentlypreferred. but nonetheless illustrative. embodiment in accordance withthe present invention. when taken in conjunction with the accompanyingdrawings, wherein:

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a perspective view ofaconventional sewing machine with a vertically disposed bobbin;

FIG. 2 is a perspective view ofa conventional sewing machine with ahorizontally disposed bobbin;

FIG 3 is a perspective view ofa bobbin constructed according to theteaching of the invention and usable in the machines of FIGS. I and 2;

FIG. 4 is an enlarged partial view of the bobbin wound with an extent ofthread thereon and positioned in a machine of the type shown in FIG. Iand with a sensor means diagrammatically illustrated in operation inaccordance with the teaching of the invention;

FIG. 5 is an enlarged partial view of the bobbin in a horizontalposition and with another embodiment of a sensor means schematicallyillustrated in accordance with the teaching of the invention; and

FIG. 6 is an enlarged partial view of a bobbin of the invention and afurther embodiment of a sensor means illustrated diagrammatically andconstructed in accordance with the teaching of the invention.

DESCRIPTION OF THE INVENTION Referring to the drawing, FIGS. 1 and 2illustrate two different types of sewing machines. In FIG. 1, the bobbinis positioned vertically whereas in FIG. 2, the bobbin is illustrated aspositioned horizontally. FIGS. I and 2 are illustrated solely to suggestthat the broad concept of the invention is not limited to any particulararrangement of sewing machine bobbin, but rather that the invention maybe utilized in any position of the bobbin in a sewing machine. For thisreason, like numerals will be utilized to designate like parts ofstructure in both FIGS. 1 and 2.

In FIGS. 1 and 2, the sewing machine generally identified by the numeralI0 includes a head 12, a foot I4, and a needle 16. Mounted beneath thesewing foot 14 is a foot plate 18 and a sliding plate 20. The slidingmovement of the plate 20 serves to cover and uncover or expose thebobbin mechanism beneath the foot plate I8. In each of FIGS. I and 2,the bobbin mechanism usually includes a bobbin carriage 22 that supportsa bobbin housing 24. All of the aforementioned structure is conventionalin sewing machines, whether the same be intended for commercial or homeuse and, therefore, the details of the same form no part of the presentinvention, except that it will be helpful but not necessary tounderstand the arrangement of such details in the functioning of thesubject matter of the present invention.

Usually mounted within the bobbin housing 24 is a bobbin. The bobbin maybe described as a spool or reel about which thread is wound. The bobbinthread provides the locking lower stitch that cooperates with the upperstitch formed by the thread 26 passed through the eye of the needle 16.For the purposes of the present invention, reference is made to the termbobbin. This term is intended to mean and to include, withoutlimitation, spools, reels and other like structures for use with suchelongated and continuous materials as thread, yarn, filaments, wire,cord and like materials that are usually wound about bobbins whetherthey be for spooling or reeling. Hence, for convenience, it is alsoimportant to recognize that throughout the disclosure, reference will bemade to the term "thread. This term is not intended to constitute alimitation upon the scope of the invention. It will be recognized bythose skilled in the art, as the description proceeds, that theinvention may be utilized not just in the sewing machine arts but inother arts including those finding it necessary to determine beforehandthe approaching end of such threads as, but not limited to, wire, yarn,filaments, cord and the like.

Referring now to FIG. 3, there is disclosed a unique bobbin generallyidentified by the numeral 28. The bobbin 28 includes a body 30 hereshown circular in shape and axially extending to provide a surface aboutwhich a thread may be wound. For convenience, the body 30 has a hollowinterior or axially directed opening 32 to render it easily applicableand mounted upon the conventional spindle that is normally provided inthe bobbin housing 24. The axial extent ofthe body 30 is a matter ofchoice. Basically, the invention comprises the body 30 about which aleading portion of a thread is adapted to be wound. The extent of thebody 30 about which such leading portion of the thread is to be wound isdelineated by a partition or wall 34. The wall 34 is positioned on thebody intermediate the ends thereof as can be more clearly seen from aside view of the bobbin in FIGS. 3, 4 and S.

Spaced from the partition wall 34 are outer walls 36 and 38. The outerwall 36 is more closely spaced with respect to the partition 34 than isthe opposite outer wall 38. Although the outer walls 36 and 38 areillustrated as defining the opposite axial ends of the bobbin structure28, it should be apparent that they need not be so located on the body30. Such outer walls 36 and 38 may be spaced slightly inward from theends of the bobbin and on the body 30.

The three walls 34, 36 and 38 are arranged substantially radially withrespect to the body 30. As illustrated in the Figures ofthe drawing. theouter walls 36 and 38 may have interior surfaces that are concave inshape while the outer surfaces thereof may be convex in shape. Theparticular shape of such walls should not constitute a limitation uponthe invention and, therefore, the particular illustration is made solelyto enable a clearer understanding of the invention. it will be notedthat the radial extent and diameter of the inner partition wall 34.although illustrated as slightly smaller. may be of equal radial size asouter walls 36 and 38. Moreover, the partition 34 is provided with oneor more notches 40 in its outer periphery to accommodate the thicknessof the thread to be wound on the bobbin. Again. the purpose and functionof such notches will become apparent as the description proceeds.

Referring to FIG. 3 and more particularly to the bobbin structure 28.the three relatively spaced walls define two winding parts on thebobbin. one of such parts. the main or larger. being defined between thepartition 34 and the outer wall 38 while the other winding part. herereferred to as the reserve space. is defined between the partition 34and the opposite outer wall 36. The main winding part is adapted tosupport. in overlying turns. the main portion of the thread that is tobe wound on the bobbin while the reserve part is adapted to support anextent or length ofthe terminal end of the thread which is deemed to besufficient to warn the operator oi the approaching end of the thread andto know well in advance of the actual end of the thread when the bobbinwill run completely out of thread.

Referring to FIG. 4, there is a bobbin 28 illustrated with thread shownpositioned thereabout. When the thread is wound about the bobbin. theterminal extent of such thread is first wound in position within thereserve space defined between the partition 34 and the outer wall 36.Thus. the bobbin is first wound wtih thread into the reserve space andis illustrated by the thread 42. The reserve or terminal end of thethread 42 is wound to the substantial full diameter of the reserve spaceof the bobbin as limited by the partition 34 and then crossed over byway of one of the notches 40 into the main winding part of the bodybetween the wall 34 and the outer wall 38. Hence, the notches 40 enablethis cross over without tearing or damaging the thread and also preventthe thread from unwinding and snarling. Thereafter, the remainder of thethread is wound on the body 30 that forms a part of the main part of thebobbin.

FIG. 4 shows the thread 42 within the reserve part of the bobbin and anextent of the thread 44 wound in the main part of the bobbin. The mainpart of the bobbin is then also wound with overlying turns of thread 44until the same reaches approximately the full diameter of the outerwalls 36 and 38 during which some turns of the thread 44 may overlie butnot entangle with the threads 42 in the reserve part. Usually, a lengthof the main winding thread 44 is permitted to extend loosely from thebobbin so when the bobbin is placed on the spindle 46 of the bobbinhousing 24, the thread will extend outwardly and be accessible throughan opening 48 in the bobbin housing. The bobbin housing is then placedwithin the bobbin carriage 22 beneath the sewing needle 16 and the plate20 is then slid to close thereover.

During the sewing operation, the upper thread 26, threaded in the needle16, engages in locking arrangement with the thread 44 of the bobbin toform the lock stitch. During the sewing operation and the formation ofstitches, the main thread 44 unwinds from the bobbin 28 until such timethat all of the thread 44 is used up from the main part of the bobbinbetween the partition 34 and the outer wall 38. At that point, thecontinued unwinding thread crosses over the partition 34 by way of thenotch 40 within which it was held and begins to unwind the reserve woundthread 42 from the reserve space. It will be understood that thepartition 34, therefore, functions as a separator between the main partof the bobbin 28 and the reserve part of the same bobbin so that theturns of the reserve and main threads 42 and 44 do not become tangledwith each other.

The cross over afforded by the partition wall 34, at the notches 40,assures that the turns 42 and 44 are continuous and that the windings 42and 44 are. therefore, contiguous and unbroken so that there is a smoothtransition of unwinding of the main turns 44 and thereafter the reserveturns 42. The notches 40 further aid in the separation of the reserveand main thread turns from each other and prevents the cross overthread. that is to say. the thread that crosses over during the initialwinding of the bobbin from the reserve turns 42 to the main turns 44,from sliding over or along the surface or rim or outer peripheral edgeof the partition wall 34. Hence. the notches retain the cross overthread in a fixed and desired position on the wall 34 until the crossover unwinding action is completed.

in windin the thread on the bobbin 26, an extent of the terrnina end ofthe thread is wound in overlying turns in the reserve part of thebobbin. These are depicted at 42. The winding is continueduninterruptedly across the partition through one of the notches 40provided thereon and the remainder portion of the thread is wound inoverlying turns 44 on the main and reserve parts of the bobb n. Thiswinding is provided such that the end of the main turns of the thread 44thereafter becomes the leading end by which the thread 44-42 issubsequently unwound from the bobbin 28 so that the turns of the thread44 must be unwound first from the bobbin before the reserve or terminalend of the same thread or turns 42 can be unwound from the bobbin.

What has been disclosed thus far is a unique bobbin adapted to support acontinuous length ofthread of any kind thereon and wound in such mannerthat the end of the thread, here defined as the reserve portion of thethread 42, can be utilized for the purpose of detecting its approachingcomplete unwinding from the bobbin and to thereafter provide theoperator using such bobbin with the knowledge that the bobbin is aboutto run out of thread. For this purpose, the bobbin 28 may be constructedin a number ofways. FIG. 4 illustrates one embodiment of such bobbin.There, the bobbin is disclosed with each of its walls 34, 36 and 38being able to permit the passage of light therethrough. To permit this,it has been found in practice that if the walls are made ofclearplastic, the same will permit the through passage of light.

Illustrated in FIG. 4 is a light source 50 that may be connected to anyconvenient source of electricity such as that powering the sewingmachine motor. The light source 50 passes through an opening that is aconventional formation in the bobbin carriage 22. The light then passesthrough the walls 38, 34 and 36 of the bobbin 28 mounted within thecarriage and within the housing 24. The housing 24 is conventionallyprovided with an opening 52 which thereby permits the light from thesource 50 to pass completely through the carriage and the housing andoutwardly therefrom to be detected by a conventional light detector 54which may also be connected to any convenient source of electricalenergy such as that shown in S6 and thereafter to a bulb or otherconvenient signal means 58. The illustrated arrangement of the sensingmeans, which in cludcs the light source 50 and detector means 54,clearly illustrates the manner in which the presence of and theprogressive unwinding of the reserve turns of thread 42 from the spool28 may be detected and a signal provided to the operator long before thethread eventually completely unwinds from the bobbin 28.

As the main turns ofthread 44 unwind from the bobbin, the light from thesource 50 is permitted to penetrate and pass through the outer wall 38to the partition 34. However, until such time as the thread in thereserve part of the bobbin starts to unwind, the light cannot penetratebeyond the partition 34. As the thread 44 is completely used up andcrosses over the partition 34 to cause the reserve turns 42 to unwind,such unwinding of the reserve thread begins to progressively exposeincreasing greater radial portions of the reserve space between thepartition 34 and the outer wall 36. This then permits the light from thesource 50 to pass in in creasing intensity through the wall 34, thereserve space and thereafter through the wall 36 and to be detected bythe light sensing means 54 which is connected with the indicator means58.

As more and more of the reserve turns of thread 42 are unwound from thereserve space, more light is permitted to pass through the reserve spaceto the sensor means 54. lf the indicator or signal means 58 is a lightbulb that may be conveniently mounted in any position here shown on thehead 12 of the sewing machine 10, the operator will be attracted by theillumination ofthe bulb 58. As more light passes from the source 50through the reserve part of the bobbin and is detected by the sensingmeans 54. the indicator bulb 58 will grow stronger in intensity toattract the attention of the sewing machine operator who will thenrealize that the reserve thread is now being unwound from the bobbin andthat the thread is approaching the terminal end of its extent.

in carrying out the method of the present invention, the main portion ofthe thread 44 is unwound from the main part of the bobbin beforeunwinding the reserve portion threads 42 from the reserve part of thebobbin. The light 50 is directed at the reserve portion of the bobbinand the light detecting means 54 is directed at that point from whichthe light is to pass through the reserve part of the bobbin so as tosense the light and thereby provide an indication to the operator thatthe reserve threads are being unwound from the reserve part of thebobbin.

in a further embodiment in FIG. 5, the outer wall 36 is constructed of amaterial to enable the passage of light therethrough while the partition34 is provided with a light reflecting surface. The light source 50 isdirected at an angle to the reflective surface of the partition 34 whilethe light sensing means 54 is also positioned at an angle to thereflecting surface of the partition 34. As illustrated in FIG. 5. boththe light source 50 and the detecting or sensing means 54 are positionedon one side of the bobbin so that as the reserve turns of thread 42 areunwound from the reserve part of the bobbin between the partition 34 andthe outer wall 36, the light will penetrate to the reflective surfaceofthe partition 34 and the reflected light will be sensed by theindicator S4 to thereby operate the signalling means 58.

In the embodiment shown in H6. 6, the outer wall 36 and the partition 34are constructed to enable the passage of light from the source 50completely therethrough to the outer wall 38 which has a reflectivesurface. Once again, both the light source 50 and the light indicator 54may be positioned on one side of the bobbin 28 with the light source anddetecting means angled such that the light from the source may passthrough the reserve part of the bobbin to be reflected back by thereflective surface of the outer wall 38 to the light sensor or detector54. Hence, as the turns of reserve thread 42 unwind from the reservepart of the bobbin defined between the partition 34 and the outer wall36, light from the source 50 will penetrate and pass through the same tothe reflective surface of the outer wall 38 and be reflected thereby tothe light indicator 54 which will then operate the signalling device 58.

The present invention discloses a unique bobbin and method of windingthe same and also an arrangement of structure for detecting theapproaching end of the thread wound upon such bobbin. The structure ofthe bobbin is simple and inexpensive. The arrangement of sensing means.which includes the light source 50 and light detector or sensor 54, maybe conveniently installed on any conventional sewing machine whether thesame utilizes a vertical or horizontal bobbin. Although the presentinvention has been disclosed and described for use in connection with asewing machine, those who are skilled in the art will readily recognizethat the teaching of the present invention may be applied with equalfacility to other machines requiring the use of bobbins, spools, reels,and the like and wherein it is important to be able to detect theapproaching end of the particular type of thread being unwound therefromWhile there have been shown and described and pointed out thefundamental novel features of the invention as applied to a preferredembodiment thereof. it will be understood that various omissions andsubstitutions and changes in the form and details of the deviceillustrated and in its operation may be made by those skilled in the artwithout departing from the spirit ofthe invention. It is the intention.therefore, to be limited only as indicated by the scope of the claimsappended hereto.

What is claimed is:

1. ln an apparatus for indicating the approaching end of a thread woundon a rotatable bobbin,

said bobbin comprising two outer walls and a partition wall spacedtherebetween such that a first portion of thread may be wound betweenone of said walls and said partition separate and contiguous with asecond portion of the thread wound between the second of said walls andsaid partition,

at least said one wall enabling the passage of light therethrough tosense the presence of thread wound between said one wall and saidpartition,

a sensor comprising a source of light directed substantiallyperpendicular to the windings of the thread to pass light through saidone wall and through said space between said one wall and partitionsubstantially perpendicular to the windings of the thread and lightdetecting means to sense the light passing through the space betweensaid one wall and said partition.

and indicator means connected with said light detecting means toindicate the intensity of light passing through the space between saidone wall and partition as the thread unwinds therefrom.

2. In an apparatus as in claim I,

each of said walls and partition enabling the passage of lighttherethrough from one side of said bobbin from said source.

and said light detecting means being on the opposite side of said bobbinto detect the intensity of the light passing through said space betweensaid one wall and partition.

3. In an apparatus as in claim 1,

one of said walls having a light reflecting surface,

said light source and light detecting means being on the same side ofsaid bobbin,

said light source being directed at said light reflecting surface suchthat the light reflected by said surface is detected by said detectingmeans.

4. ln an apparatus as in claim 3,

said one of said walls having a light reflecting surface being saidpartition wall.

5. In the method of determining the approaching end of a thread wound ona bobbin wherein the thread has a main portion thereof wound on one partof a bobbin contiguous with a terminal portion of the thread wound onanother part of the same bobbin having a transparent outer wall, themethod comprising unwinding the thread from the one part of the bobbinprior to unwinding the terminal portion from the other part of thebobbin,

directing light at the thread through the transparent outer wall of thebobbin from a direction substantially perpendicular to the unwindingdirection of movement of the thread wound in the other part of thebobbin,

and directing a light detecting means in the direction from which thelight directed at the other part of the bobbin is to be received toindicate the intensity of light passing through the other part of thebobbin.

6. In the method as in claim 5,

and indicating the presence and intensity of light passing through theother part of the bobbin as the terminal portion of the thread isunwound therefrom.

1. In an apparatus for indicating the approaching end of a thread woundon a rotatable bobbin, said bobbin comprising two outer walls and apartition wall spaced therebetween such that a first portion of threadmay be wound between one of said walls and said partition separate andcontiguous with a second portion of the thread wound between the secondof said walls and said partition, at least said one wall enabling thepassage of light therethrough to sense the presence of thread woundbetween said one wall and said partition, a sensor comprising a sourceof light directed substantially perpendicular to the windings of thethread to pass light through said one wall and through said spacebetween said one wall and partition substantially perpendicular to thewindings of the thread and light detecting means to sense the lightpassing through the space between said one wall and said partition, andindicator means connected with said light detecting means to indicatethe intensity of light passing through the space between said one walland partition as the thread unwinds therefrom.
 2. In an apparatus as inclaim 1, each of said walls and partition enabling the passage of lighttherethrough from one side of said bobbin from said source, and saidlight detecting means being on the opposite side of said bobbin todetect the intensity of the light passing through said space betweensaid one wall and partition.
 3. In an apparatus as in claim 1, one ofsaid walls having a light reflecting surface, said light source andlight detecting means being on the same side of said bobbin, said lightsource being directed at said light reflecting surface such that thelight reflected by said surface is Detected by said detecting means. 4.In an apparatus as in claim 3, said one of said walls having a lightreflecting surface being said partition wall.
 5. In the method ofdetermining the approaching end of a thread wound on a bobbin whereinthe thread has a main portion thereof wound on one part of a bobbincontiguous with a terminal portion of the thread wound on another partof the same bobbin having a transparent outer wall, the methodcomprising unwinding the thread from the one part of the bobbin prior tounwinding the terminal portion from the other part of the bobbin,directing light at the thread through the transparent outer wall of thebobbin from a direction substantially perpendicular to the unwindingdirection of movement of the thread wound in the other part of thebobbin, and directing a light detecting means in the direction fromwhich the light directed at the other part of the bobbin is to bereceived to indicate the intensity of light passing through the otherpart of the bobbin.
 6. In the method as in claim 5, and indicating thepresence and intensity of light passing through the other part of thebobbin as the terminal portion of the thread is unwound therefrom.